@article{FPM_2013_18_6_a4,
     author = {K. V. Golubev},
     title = {A differential equation on the cover function of the hexagonal lattice by the trivalent tree},
     journal = {Fundamentalʹna\^a i prikladna\^a matematika},
     pages = {91--94},
     publisher = {mathdoc},
     volume = {18},
     number = {6},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FPM_2013_18_6_a4/}
}